IPv6 neighbor discovery packets on startup


I am using Cumulus Linux 2.5.7

I am observing ICMPv6 Neighbor Solicitations and Listener Reports on all front ports when Cumulus Linux boots. Is there a way to disable this neighbor discovery?

Thanks!

5 replies

Userlevel 4
Yes
https://support.cumulusnetworks.com/hc/en-us/articles/204184298-Disabling-IPv6-EUI-64-Link-local-Add...
Thank you very much for the quick response!
If I may ask a followup question, what is the recommended way to specify a bridge in /etc/network/interfaces that does not assign the bridge an IPv6 address?

For example,

auto br1000
iface br1000
bridge-ports swp1 swp2

Will result in a bridge:

# ip addr show br1000
57: br1000: mtu 1522 qdisc noqueue state UP
link/ether 00:25:90:b2:16:d1 brd ff:ff:ff:ff:ff:ff
inet6 fe80::225:90ff:feb2:16d1/64 scope link
valid_lft forever preferred_lft forever

I would like to initialize the bridge without an IPv6 address.

Userlevel 4
Hey Bryan

You have two options that I know about. I was looking through the source code for ifupdown2 and don't see a /etc/network/interfaces knob to disable IPv6. It seems trivial to add but its not that common of an ask because disabling IPv6 can break functionality in certain applications (i.e. BGP Unnumbered RFC5549). However these are both easy options and easy to automate.

  1. Disable a bridge individually echo 1 > /proc/sys/net/ipv6/conf//disable_ipv6
  2. Disable IPv6 alltogether on the switch echo 1 > /proc/sys/net/ipv6/conf/all/disable_ipv6
Thank you again.

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